Abstract
In this paper, we will examine how the plant
hormone Ethylene affected the growth and development of Paperwhite Bulbs
(Narcissus Papyraceus). It should be noticed that leaves, fruits, and flowers
are the target sites of ethylene. They allow the onset of the conditions
suitable for organ longevity, stage progression, and reproductive success. Any
change in ethylene’s level or perception can directly or indirectly impact the
lifespan of this plant (Khan 2014). We had paid special attention to the
sophisticated network of ethylene crosstalk and intended to share data for
future research. An extensive range of effects, including physiological and
morphological, were observed during this experiment. We found that ethylene
allowed roots and shoots to grow in some bulb species, promoted flower-bud
abscissions in leaf and lily of the hyacinth, and evoked different diseases
like a flower-bud blast, bud necrosis, and gummosis. These changes could never
be observed if we had tried any other plant hormone (Ent and Pieterse 2012).
Introduction
Earlier this year, during the winter season,
we collected data for labs and observed how ethylene affects the growth and
development of paperwhite bulbs. Narcissus papyraceus is one of the most
popular species of bulbous plant. It is mainly found in Portugal, Greece,
Algeria and Morocco. This plant species is also grown in Texas, Louisiana,
California, Azores and Corsica. Its white flowers grow in the form of bunches
and contain a lot of fragrance. Paperwhite bulbs are mostly grown as
houseplants. Ethylene (C2H4) is one of those plant hormones that can impact the
growth and development of not only paperwhite bulbs but also other similar
plants. This gas was used in our experiment. Fruits like bananas and apples
produce ethylene in a large quantity (Vandenbussche 2012). The research
question we explored in this experiment is: how ethylene impacts the growth and
development of paperwhite bulbs (Narcissus papyraceus)? In order to obtain the
answer of this question, we had divided the lab into following three parts:
o An experiment that we carried out in which
the paperwhite bulbs were planted. Their growth was measured every two days and
we repeated the process for 28 days.
o We analyzed the amount of ethylene given off
by bananas and apples.
o In the final stage, we observed how ethylene
impacted the development of flowers.
It should be noticed that ethylene is a
flammable, colorless gas having a musky and faint smell. It is one of the
simplest alkenes and is extensively used in the chemical industries. At a large
scale, more than 120 million tons of ethylene is produced every year, and much
of it is used in lab experiments and research. As an important plant hormone,
ethylene is used in fields to help fruits ripen (Binder et al. 2012). Different
environmental conditions greatly impact the development and growth of
paperwhite bulbs. Ethylene, as per our observation, had influenced the nutrient
remobilization and photosynthetic capabilities of the plant. It also controlled
the senescence of Narcissus Papyraceus. Thus, we can say that ethylene is a
multifunctional, powerful phytohormone that is capable of regulating growth and
development of Narcissus Papyraceus. It efficiently governed the growth and
development of flowers, fruits, and leaves, and promoted and induces senescence
based on its optimal and sub-optimal levels. It is interesting to know that the
same plant hormone influenced both growth and development of Narcissus
Papyraceus, and regulated different processes naturally (Pech et al. 2012).
Methods
& Materials
In this experiment, we had used apples as the
primary source of ethylene and exposed Narcissus Papyraceus to the apples for
0, 2 and 4 days (Grierson 2012). The control was zero day, and the apparatus
was set up in the following way.
o Each apparatus had 1 pot containing bulb and
soil, an apple, skewer, pop bottle and two elastic bands.
o It was actually a closed system that
contained ethylene in said quantity. To obtain ethylene in that quantity, we
mainly relied on apples.
o Each pot had one plastic bottle in it.
This experiment had three different Treatment
Groups:
o The first group was known as a control group.
In it, we didn’t use any ethylene for four days. Also, we placed no apples in
the plant pots.
o In the treatment 1 group, low amount of
ethylene was used (n=5 bulbs, one bulb per pot). Apples were not placed in the
pop bottle for about two days.
We had a chance to work in a group of 3
individuals. First of all, we assembled apparatus in order to measure the
effects of ethylene on Narcissus Papyraceus or paperwhite bulbs (Grierson 2012).
We continued our experiment in the following steps:
o In the first step, we planted 15 bulbs, one
per pot, in the greenhouse.
o Then we filled the pots and planted more
bulbs until the soil came up to the bottom of green shoots.
o We continued watering the pots thoroughly.
o Once the soil was fully settled, we measured
the distance of the tip of bulb from the soil.
o Later on, we measured the distance of the
soil from the tip of longest leaf to know how ethylene had impacted the growth
of this plant.
o After a few days, plastic bottles, with or
without apples, were removed to observe how paperwhite bulbs would grow in
their absence.
o For nearly a month, we watered the plants in
the greenhouse.
o On day 28, we collected data and it was the last
day of our experiment.
The data was collected in the following, two
forms:
o Length of the longest leaf was measured in
every pot.
o We observed the flowering status of the plant
(days on which buds were developed and flowers appeared).
The data collected through this experiment
formed the basis of two variables.
o Variable 1: Plant growth was indicated by the
length of the longest leaf.
o Variable 2: The development of flowers helped
us determine the time needed for bud development.
Results
Microscope, slides, coverslips, stains,
micrometers, spectrophotometer, paper chromatography, measuring sticks,
weighing balance were all used to obtain accurate results. After this
experiment, we found that the growth and development of paperwhite bulbs is
affected by different endogenous hormones and environmental factors, ethylene
being one of them (Bogatek and Gniazdowska 2012). It is a natural process that
is regulated by transcriptional regulators, mechanical properties of tissues,
and of course, phytohormones. In simple words, we can say that apples, unlike
bananas, are a rich source of ethylene and can be placed in any pot or directly
in the soil to get lots of paperwhite bulbs in just one month. This experiment
confirmed the growth and development of the leaves. We found that ethylene
directly impacted the length of leaves, and that the leaves receiving more
ethylene grew in length rapidly. It was also found that ERF5 and ERF6 help
increase the length of leaves and allow flowers to grow at a fast speed. The
concentration of ethylene was increased and decreased by placing and replacing
apples every four days (Gonzalez-Carranza and Roberts 2012).
Discussion/Summary
It has now been revealed that there is a
correlation between the growth and development of paperwhite bulbs and
concentration of ethylene. Some of the leaves tend to grow better than the
others because they are more responsive to ethylene in the plant pots. At the
same time, the leaves not growing to that length were least responsive to this
plant hormone. Paperwhite bulbs showed relatively lower growth when ethylene
was not available to them in a high concentration, and when the apples
producing ethylene were removed from the pots for a day or two. Both nitric
oxide and reactive oxygen species, which are up-regulated by this plant
hormone, could be involved in this experiment. That’s because they help in
plant growth especially leaf expansion, but we didn’t use them and tried to
keep things simple and understandable (Cho et al. 2012).
In conclusion, we can say that ethylene plays
a major role in the growth and development of not only paperwhite bulbs but
also other plants. The concentration of this plant hormone directly impacts the
length of leaves and development of buds. It is capable of triggering the networks
of signaling pathways and can impact phytohormones regulation to an extent.
Unlike bananas, apples are a good source of ethylene and can be easily used in
experiments like this. Their presence and absence impacted the length of leaves
and bud development. Last but not the least, we should investigate the
involvement and role of ethylene and other plant hormones at post-translation
levels (Arshad and Frankenberger 2002).
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